Waaterpal, I'm sorry for your experience. I am sure you probably feel sick that you let it happen, and by your post, you most likely feel violated. It may not appear to be a violation to many, but by waaterpal's post, I take it she does, and it should be treated as such.
A lot of women can probably relate to this conditioning. And yes, women all over the world are learning to put their big girl panties on and stand up for themselves in situations such as this. However, consider, waaterpal is still a fairly new diver, and is diving in a another country. Who knows what the dive etiquette is? We only learn through others telling us, reading, or experience. Plus, consider background, how one was raised, and conditioning. It's easy to say put your big girl panties on and stand up for yourself, however, if you have ever been a woman in a situation where you someone was forcing themselves on you, we know in our minds what we would/should do, but often when it faces you, it is often another monster. I say this from experience.
Waaterpal, I would write a letter to the dive shop and let them know about the situation and your experience, and let them know you expect some sort of a reply.
Again, I am sorry you had this experience, and, I suspect next time you will react differently.